Walking tractor tread driving mechanism



Feb. 13, 1951 A. F. BUSICK, JR, ET AL 2, 4 ,4

WALKING TRACTOR TREAD DRIVING MECHANISM Filed May 4, 1945 6 Sheets-Sheet l INVENTOR.

Feb. 13 1951 A. F. BuslcK, JR, ET AL 2,

WALKING TRACTOR TREAD DRIVING MECHANISM 6 Sheets-Sheet 2 Filed May 4, 1945 Tang I mam . INVENTOR. HER/EN FEUS/E k j/f JL/HQRY FETDQK ATTORNEY.

Feb. 13, 1951 A. F. BUSICK, JR., ETAL 2,541,496

WALKING TRACTOR TREAD DRIVING MECHANISM 6 Sheets-Sheet 3 Filed May 4, 1945 Feb. 13, 1951 A. F. BUSICK, JR., ET AL ,4

WALKING TRACTOR TREAD DRIVING MECHANISM Filed May 4, 1945 6 Sheets-Sheet 4 Feb. 13, 1951 A. F. BuslcK, JR, ET AL 2,541,496

WALKING TRACTOR TREAD DRIVING MECHANISM Filed May 4, 1945 6 Sheets-Sheet 5 INVENTOR.

HDk/EA [Bus/ax L/ Y HE Y F5105:

ET AL 2,541,496

Feb. 13, 1951 A. F. BUSICK, JR,

WALKING TRACTOR TREAD DRIVING MECHANISM 6 Sheets-Sheet 6 Filed May 4, 1945 INVENTOR. H171 /E/V Ffius/c/r L/R HHEEY F 5705K ATTORNEY.

Patented Feb. 13, 1951 UNITED STATES WALKING TRACTOR TREAD' DRIVING MECHANISM Adrien F. Busick, lira, and Harry F. Stock, Marion,

Ohio, assignors to Marion Power Shovel Company, a corporation of Ohio Application May 4, 1945, Serial No. 592,028

14 Claims.

This invention relates to a walking tractor of the type shown in Patent No. 2,179,765, granted November 14, 1939 to Harry F. Stock, and more particularly to the operating devices which alternately advance the treads and the body of the machine and the actuating devices therefor.

As shown in that patent the platform and base, which constitute the main or body portion of the machine, are connected one with the other for upward and forward movement in unison, and treads are arranged at the respective sides of the body. Suitable operating devices, shown in the patent as levers, are connected at their lower ends with the respective treads and are pivotally connected at their upper ends with cranks on the adjacent ends of a driving shaft on the platform and the movement of the operating devices by the cranks so controlled that upon each rota ticn of shaft the treads will be lifted and moved forwardly into engagement with the ground in advanced positions and the body of the machine will then be moved upwardly and forwardly a. like distance. These machines are extremely heavy and, of course, increase in weight as the capacity or" the machine is increased As the machines have increasedin size and load capacity the dimensions of the driving shaft, cranks and associated parts, have increased to such an extent as to involve serious production problems, and one object of this invention is to provide op atih-g devices and actuating mechanism therefor which will be free from these objectionable characteristics.

A further object of the invention is to provide such a mechanism in which the weight or" the load will be imposed on each operating device through a plurality of actuating devices, instead oithrough a single actuating device as in the above mentioned patent.

A furtl'ier object of the invention is to pro.- vide a walking mechanism which will advance the machine in relatively long steps without the use of controlling means other than the actuating devices.

step may be varied by an adjustment or" the actuating devices for each tread with relation one to the other.

A further object of the invention is to provite such a mechanism in which each operatin device is actuated by two eccentric devices, such as cranks, which will advance the machine in eachcperating cycle a distance materially more than double the throws of the eccentric devices.

A further object or" the invention is to provide sucha mechanism which is simple in constructionand of a strong durable construction.

Other objects of the invention may appear as the machine is described in detail.

In the accompanying drawings Fig. 1 is a side elevation of a machine embodying the invention, partly broken away; Fig. 2 is a plan View of the machine with the superstructure remove-cl; Fig. 3 isa pian view of one of the o erating devices and its actuating mechanism; Fig. i is an end elevation of one of the operating devices and its actuating. mechanism, partly in section; Figs. 5 and 6 are detail views of one of the operating devices showing the same in diiierent operative positions; Fig. 7 is an elevation of a modified form of operating device and actuating devices; and Fig. 8 is a sectional view of g device of Fig. '7.

n th to drawings we have illustrated one emmerit of the invention and have shown the 111% as instal d onan excavating machine but it is to be understood that the invention may take vaious forms and may be installed on or used in connection with machines of various kinds.

The machine shown inthe drawings is a drag line excavator and the main or body portion thereof comprises a circular base iii on which a platform H is. mounted for rotation about a ver ticalaxis E2. The excavating mechanism is not shown but the usual dragline bucket is carried-by boom, a portion of which is shown at it, and which is pivotally mounted on the rear end of tie platform, the terms front and rear bei e hereinused with relation to the direction in 2 ch the machine is propelled, that is, to the right in Figs. 1 and 2. The excavating mechanism is actuated through the usual cables and mechanism mounted on the platform, including a drag drumv i i'driven by motors l5 and a hoisting drum iii driven by motors ll.

Treads l8. are arranged at the opposite sides of the body. of the machine and are connected by operating devices i9 withactuating mechanism on the platform, this actuating mechanism comprising separate but identical actuating units 22a for the respective operating devices, these actuating units being operated in unison and preferably being connected with a common source of power. In the presentmach'ine the platform is provided with lateral extensions 2%] which support the respective actuating units and which are strongly, braced against longitudinal or vertical displacement, as shown at 25 and 22'. The actuating devices for the operating devices may be of any suitable character and, in the present instance, each unit comprises two transverse shafts 23. and i i'spaced laterally one from the other at'onecside of the body, each shaft being J'ournaled'adjacent its respective ends in bearings 25 and 2 Rigidly secured to the shafts ZS'and. 2d adjacent their inner ends are gears 21 and 2t. A driving shaft 29 extends transversely to the platform and is journaled in bearings til'and 3|. Adjacent each end the shaft 29 has secured thereto a pinion 32 which meshes with the gears 2'! and 28 of the adjacent actuating unit, and thus serves to rotate the four shafts of the two units simultaneously in the same direction and at the same speed. The driving shaft may be driven from any suitable source of power. In the particular arrangement illustrated driving gears 33 are secured to the shaft and mesh with pinions 34 which are adapted to be connected by means of clutches 35 with the driving mechanism for the drag cable drum It, so that by disconnecting that mechanism from the drums and connecting it with the drive shaft 29 the latter may be rotated by the motors l5.

The operating devices I9 at the respective sides of the machine are identical one with the other and are connected with their actuating devices in the same manner. Each operating device is operatively connected at its lower end with the corresponding tread l8 and is connected adjacent its upper end with the two shafts of the adjacent actuating unit in such a manner that the rotation of those shafts will advance the tread and the body of the machine alternately. In the arrangement here shown, see Figs. and 6, the lower end of the operating device is pivotally mounted on a trunnion member 35 for movement about an axis 36a transverse to the tread, the trunnion member being mounted on the tread for movement about an axis extending lengthwise of the tread, in bearings 31, to permit the tread to accommodate itself to the contour of the ground surface. In the present construction each trunnion member 36 is provided between its ends with laterally spaced apertured parts 536, and a bearing l3? adjacent the lower end of the operating member !9 extends between the parts I35 and is connected therewith by a pivot pin I38. The upper end portion of the operating device is of a substantial fore and aft width and when the operating device is pivotally connected with the tread the upper portion thereof is preferably of a width substantially greater than the width of the lower portion thereof. In the construction here shown the operating device is approximately triangular in shape and is formed in one piece. It will be understood, however, that the operating device may be of any suitable character and may be cast, fabricated, or otherwise constructed. In its upper portion the operating device is provided with laterally spaced bearings 36 and 39, which, in the present instance, are arranged adjacent the upper apices of the triangle. Each of the actuating shafts 23 and 24 has secured thereto, adjacent the operating device, an individual actuating device or member adapted to be rotatably mounted in the corresponding bearing in the operating device on an axis which is eccentric to the axis of the shaft with which it is connected. In the present construction these members are in the form of cranks 46 and BI rigidly secured respectively to the shafts 23 and 24 and having adjacent their outer ends crank pins 32 and 43 mounted respectively in the bearings 38 and 39. Thus the. load on the machine is distributed between the four actuating shafts of the two actuating units and the rotation of the cranks serves to advance the machine and the treads successively.

In Fig. 5 there is shown one tread and its operating device with the several parts in the positions which they occupy when the tread l8 first contact with the ground after having been moved to its advanced position. It will be noted that the pivotal connection between the opating device and the tread is somewhat in advance of the vertical axial plane of the main driving shaft 25, which is indicated by the line a l. The continued rotation of the shafts 23 and 25 after the tread is in contact with the ground causes the cranks to fulcrum on the bearings of the operating device and to rotate about the axes of those bearings, thereby moving the shafts 23 and 2s, and therefore the body of the machine, upwardly, forwardly and then downwardly into engagement with the ground. This movement of the shafts and body rocks the operating dev'ice forwardly about its pivotal connection with the tread and carries the center line it of the driving shaft forwardly beyond that pivotal connection, as shown in Fig. 6, where the parts are in the positions which they occupy just before the tread is moved out of contact with the ground. When the body of the machine thus rests on the ground, with parts in the positions shown in Fig. 6, the continued rotation of the shafts 2 3 and 2d causes the cranks to fulcrum on the shaft bearings on the body and lift the operating device and tread and move the latter to the forwardly advanced position shown in Fig. 5. The cranks 4B and ll may be parallel one with the other or one crank may be advanced with relation to the other, as by securing the same to its shaft in an advanced position when the machine is assembled. When the cranks are parallel the point of connection 36a between the operating device and the tread will 'move substantially in a semi-circle upon each advancement of the tread and the length of each step of advancement will be'equal to twice the length of the throw of one of the eccentric actuating devices, that is, twice the distance between the axis of the actuating shaft and the axis of the crank pin connected with that shaft. In the present instance the throw of each crank is twenty-four inches and therefore the step would be four feet in length.

The length of the step may be varied by advancing the crank of one shaft with relation to the crank of the other shaft and in the present arrangement the crank 2i has been advanced with relation to the crank 38. As shown in Fig. 5 the crank ii extends forwardly from the shaft 23 with the axis of its pin 42 on a line 55 which extends through the axes of the shafts 23 and 24, and the crank il has been so advanced that the axis of its 4-3 lies on a radial line extending. downwardly and forwardly at an angle of approximately forty degrees to the line 55. connection between the advanced crank 4| and the operating device is such as to permit a fore and aft movement of the pin 43 with relation to the operating device. In the present construction the bearing 39 for the pin 63 of the crank 4| is in the form of a block slidably mounted in a guideway 15 formed between upper and lower portions of the operating device and closed at its rear end by a plate ll. Due to the advanced position of the crank All with relation to the crank as the operating device is caused to oscillate about the pin 42 of crank 4i) alternately in. opposite directions during each cycle of operations. As the tread is moved forwardly with relation to the body of the machine the operating device moves about the pin .2 in a counterclockwise direction from the position shown in Fig. 6 to the position shown in Fig. 5, and as the body is moved forwardly with relation to the tread the operating devic moves about the pin Q2 in a clockwise direction from the position shown in The- Fig. 5 to the position shown in Fig. 6., These oscillations of the operating device cause the pivotal connection 36a between the operating device and the tread to move in an elliptical path instead of a circular path, thereby materially increasing the forward movement of the tread and of the body. When the tread engages the ground at the end of its forward movement with relation to the body the operating device is tilted rearwardly about its point of connection 361]. with the tread and that point of connection is a substantial distance in advance of a vertical center line at, as above explained, and the continued rotation of the shafts 23 and 24 causes the cranks to fulcrum on the respective bearings of the operating device to advance the body of the machine. The rear crank 5! being in advance of the front crank 4% moves its bearing 39 rearmovement to the shafts 23 and 24 and to the body of the machine. When the body comes to rest on the ground the operating device is tilted forwardly as shown in Fig. 6, and the vertical center line 54 has moved forwardly beyond the axis of the connection 36a between the operating device and the tread. Upon the further rotation of the shafts 23 and 24' the pin 43 of the rear crank il moves its bearing forwardly and downwardly with relation to the front bearing, thereby oscillating the operating device counterclockwise about the pin 42 and moving the lower end of th operating device and the tread forwardly a distance substantially greater than the throw of the cranks. In the present construction the length of the step is fifty percent greater than it would be if the cranks are parallel, that is, each step is six feet in length instead of four feet.

As has been stated, the advancing movement may be efiected by the use of eccentric devices other than cranks and in Figs. '7 and 8 we have shown an embodiment in which the connections are in the form of conventional eccentrics. As shown in these figures, the shafts 23a and 24a are rigidly connected at their ends with circular members all and 49, the axes of which are eccentric to the axes of the respective shafts, and the rear eccentric 59 is advanced forty degrees with relation to the front eccentric 48. The front circular member d8 is mounted in a circular opening or bearing 53 in the operating device l9a, and the rear circular member d9 is mounted for fore and aft movement with relation to the operating device in an elongate opening 5!, so that the movements imparted to the operating device by the eccentrics are substantially the same as the movements imparted thereto by the cranks. Both eccentrics, i8 and 49, are provided with flanges 52 and 53 to retain them in the bearing openings of the operating device.

While we have shown and described one embodiment of our invention, and a minor modification thereof, we wish it to be understood that we do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described our invention, what we claim as new and desire to secure by Letters Patent, is:

1. In a walking tractor comprising a body and a tread, two transverse shafts spaced laterally one from the other on said body, means for rotating said shafts, an operating device operatively J connected with said shafts on axes spaced radially from the axes of the respective shafts, the radius of the connection between said operating device and one of said shafts extending at an angle to the radius of the other of said connections, and

an operative connection between said operating device and said tread.

2. In a walking tractor comprising a body and a tread, two transverse shafts spaced laterally one from the other on said body, means for rotating said shafts, an operating device operatively connected with said shafts on axes spaced radially rom the axes of the respective shafts, the radius of the connection between said operating device and one of said shafts extending at an angle to the radius of the other of said connections, said operating device and the axis of its connection with one of said shafts being relatively movable, and an operative connection between said operating device and said tread.

3. In a walking tractor comprising a body and a tread, driving mechanism on the said body including two eccentric members adjacent one side of said body and means for rotating said members simultaneously in the same direction, an operating device pivotaliy connected at laterally separated points with the respective members on parallel axes, the point of connection. of said operating device with one of said members being angularly advanced with relation to its point of connection with the other of said members, and an operative connection between said operating device and said tread.

4. In a walking tractor comprising a body and a tread, driving mechanism on the said body including two eccentric members adjacent one side of said body and means for rotating said members simultaneously in the same direction, an operating device pivotally connected at laterally separated points with the respective members on parallel axes, the point of connection of said operating device with one of said members being angularly advanced with relation to its point of connection with the other of said members and being movable with relation to said operating device, and an operative connection between said operating device and said tread.

5. In a walking tractor comprising a body and a tread, driving mechanism on said body including two cranks adjacent one side of said body and means for rotating said cranks simultaneously in the same direction about laterally spaced axes, one of said cranks being in an angularly advanced position with relation to the other crank, each crank having a crank pin, an operating device having bearings in which the respective crank pins are mounted, and an operative connection between said operating device and said tread.

6. In a walking tractor comprising a body and a tread, driving mechanism on said body including two cranks adjacent one side of said body and means for rotating said cranks simultaneously in the same direction about laterally spaced axes, one of said cranks being in an angularly advanced position with relation to the other crank, each crank having a crank pin, an operating device having bearings in which the respective crank pins are mounted, one of said bearings being movable toward and from the other bearing, and an operative connection between said operating device and said tread.

Z. In a walking tractor comprising a body and a tread, driving mechanism on said body inclu'd-' ing two cranks adjacent one side of said body and means for rotating said cranks simultaneously in the same direction about laterally spaced axes, one of said cranks being in an angularly advanced position with relation to the other crank, each crank having a crank pin, an operating device having in its upper portion a fixed bearing mounted on one of said crank pins and also having a guideway, a second bearing movable in said guideway toward and from said fixed bearing and mounted on the crank pin of said advanced crank, and a pivotal connection between the lower portion of said operating device and said tread.

8. A walking tractor comprising a body, treads on the respective sides of said body, two transverse shafts supported one in front of the other at each side of said body above the respective treads, means for rotating the four shafts simultaneously in the same direction, a crank secured to each shaft and having a crank pin, the rear crank at each side of said body being positioned angularly in advance of the adjacent front crank, and an operating device at each side of said body operatively connected with the corresponding tread and having in its upper portion bearings in which the adjacent crank pins are mounted, the bearing for the crank pin of said rear crank being movable toward and from the bearing for the crank pin of the front crank.

9. A walking tractor comprising a platform, treads at the respective sides of said platform, two shafts mounts-done in front of the other on each side of and projecting beyond said platform, a transverse driving shaft having at its ends geared connection with the four first mentioned shafts to rotate the same simultaneously in the same direction, a crank secured to the outer end portion of each of the first mentioned shafts and having a crank pin, the rear cranks being positioned angularly in advance of the front cranks, an operating device at each side of said platform pivotally connected with the corresponding tread, each operating device having a fixed bearing mounted on the crank pin of the adjacent front crank and having in the rear of said bearing a slot, and a bearing slidably supported in said slot and mounted on the crank pin of the adjacent rear crank.

10. In a walking tractor comprising a body and a tread, laterally spaced shafts mounted on said body, means for rotating said shafts simul taneously in the same direction, a circular member rigidly connected with each shaft eccentric to the axis of said shaft, an operating device having laterally spaced openings to receive the respective eccentric members and supported thereby, one of said openings being of a length greater than the diameter of the eccentric member mounted therein and said eccentric member being positioned in advance of the other eccentric member, and an operative connection between said operating device and said tread.

11. A walking tractor comprising a body, treads atthe respective sides of said body, operating devices operatively connected with the respective treads, means on said body for actuating said operating devices to successively advance said body and said treads, the actuating means for each operating device including members rotatably connected with said operating device at separated points, said points of connection being differently located with relation to the axes of the respective members to cause said operating device to oscillate alternately in opposite directions about one of said points of connection during each cycle of operation of said operating device.

12. A walking tractor comprising a body, treads at the respective sides of said body, rigid operating devices pivotally connected with the respective treads and each having bearings above said pivotal connection and on the respective sides of the vertical plane of the axis thereof, means on said body for actuating said operating devices to successively advance said body and said treads, the actuating means for each operating device including eccentric members mounted in the respective bearings of said operating device, the point of connection of said operating device with one of said eccentric members being angularly advanced with relation to its point of connection with the other of said members to cause said operating device to oscillate alternately in opposite directions about one of said members during each cycle of operation of said operating device.

13. An operating device for a walking tractor of the type comprising a body, a tread, two eccentric members mounted on said body above said tread, means on said body for rotating said eccentric members and an operating device connecting said eccentric members with said tread; said operating device comprising a rigid upright member having in its lower portion a bearing by means of which it may be pivotally connected with said tread, and having in its upper portion two spaced bearings to receive the respective eccentric members, one of said upper bearings being fixed with relation to said rigid member and the other of said upper bearings being movable toward and from said fixed bearing.

14. An operating device for a walking tractor of the type comprising a body, a tread, two eccentri members mounted on said body above said tread, means on said body for rotating said eccentric members and an operating device connecting said eccentric member with said tread; said operating device comprising a rigid upright member having in its lower portion a bearing by means of which it may be pivotally connected with said tread and having a relatively wide upper portion, said upper portion having adjacent one lateral edge thereof a fixed bearing to receive one of said eccentric members and having adjacent the other lateral edge thereof a transverse slot, and a bearing slidably mounted in said slot and adapted to receive the other of said eccentric members.

ADRIEN F. BUSICK, JR. HARRY F. STOCK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 930,271 Crell Aug. 3, 1909 1,232,689 Johnson July 10, 1917 1,392,597 Ricardo Oct. 4, 1921 2,151,695 Goddard Mar. 28, 1939 2,179,765 Stock Nov. 14, 1939 FOREIGN PATENTS Number Country Date 9,240 Great Britain June 23, 1915 

